The need for new antimicrobial agents that prevent or treat plant and animal diseases increases as pathogens gain resistance to existing antimicrobials. In agriculture, available approaches for inhibiting and preventing crop and seed loss due to fungal diseases are inadequate in many cases. Fungi, e.g., basidiomycetes and ascomycetes, and fungi-like pathogens, e.g., oomycete, are significant causes of disease in many seeds and plants, including tobacco, grains, fruits, and vegetables, as well as grasses, e.g., turfgrass. In 1979, an epidemic of blue mold (caused by the oomycete Peronospora tabacina) caused an estimated $1.1 billion loss of tobacco crops in Ontario.
Furthermore, the use some currently marketed topical fungicides have drawbacks, e.g., some are thought to be hazardous to the environment, toxic to mammals, or raise other public concerns (e.g., concerns about the possible estrogenic properties of “natural” paraben preservatives in cosmetics). Thus there is a need for alternative natural antimicrobial agents that do not have these perceived disadvantages.